WO2020048634A1 - Procédé de séparation cryogénique d'air et système de séparation d'air - Google Patents

Procédé de séparation cryogénique d'air et système de séparation d'air Download PDF

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Publication number
WO2020048634A1
WO2020048634A1 PCT/EP2019/025280 EP2019025280W WO2020048634A1 WO 2020048634 A1 WO2020048634 A1 WO 2020048634A1 EP 2019025280 W EP2019025280 W EP 2019025280W WO 2020048634 A1 WO2020048634 A1 WO 2020048634A1
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Prior art keywords
pressure level
compressed air
pressure
air
stream
Prior art date
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PCT/EP2019/025280
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German (de)
English (en)
Inventor
Alexander Alekseev
Dimitri GOLUBEV
Patrick Brandl
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Linde Aktiengesellschaft
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Publication of WO2020048634A1 publication Critical patent/WO2020048634A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04387—Details relating to the work expansion, e.g. process parameter etc. using liquid or hydraulic turbine expansion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/10—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/42—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/12—Particular process parameters like pressure, temperature, ratios

Definitions

  • the invention relates to a method and a plant for obtaining an air product according to the respective preambles of the independent claims.
  • Air separation plants have rectification column systems which can be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three- or multi-column systems.
  • rectification column systems which can be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three- or multi-column systems.
  • Rectification columns for the production of nitrogen and / or oxygen in a liquid and / or gaseous state ie the rectification columns for nitrogen-oxygen separation, rectification columns for the production of further air components, in particular the noble gases krypton, xenon and / or argon, can be provided. Even if corresponding rectification columns for the extraction of further air components are not specifically discussed below, they can also be the subject of the present invention.
  • the rectification columns of the rectification column systems mentioned are operated at different pressure levels.
  • Double column systems have a so-called high pressure column (also referred to as a pressure column, medium pressure column or lower column) and a so-called low pressure column (also referred to as an upper column).
  • the pressure level of the high pressure column is, for example, 4 to 6 bar, preferably about 5.5 bar.
  • the low pressure column is operated at a pressure level of, for example, 1.3 to 1.7 bar, preferably approximately 1.5 bar.
  • the pressure levels given here and below are absolute pressures which are present at the top of the columns mentioned. The values mentioned are only examples that can be changed if necessary.
  • So-called main compressors / post-compressors Mainn Air Compressor / Booster Air Compressor, MAC-BAC processes or so-called
  • High air pressure (HAP) processes can be used.
  • the main compressor / post-compressor process is the rather
  • the main compressor / post-compressor process is characterized in that only a part of the total amount of feed air supplied to the rectification column system is compressed to a pressure level that is significant, i.e. is at least 3, 4, 5, 6, 7, 8, 9 or 10 bar, above the pressure level of the high pressure column. Another part of the amount of air used is only the pressure level of the high pressure column or a pressure level that is not more than 1 to 2 bar from the pressure level of the
  • High-pressure column differentiates, compresses, and is fed into the high-pressure column at this lower pressure level.
  • An example of a main compressor / post-compressor process is shown by Häring (see above) in Figure 2.3A.
  • Rectification column system total amount of feed air supplied
  • Compressed pressure level that is, i.e. is at least 3, 4, 5, 6, 7, 8, 9 or 10 bar above the pressure level of the high pressure column.
  • the pressure difference can be up to 14, 16, 18 or 20 bar, for example.
  • High air pressure processes are known for example from EP 2 980 514 A1 and EP 2 963 367 A1.
  • the present invention is used in particular in air separation plants with so-called internal compression (IV, internal compression, IC).
  • IV internal compression
  • internally compressed gaseous oxygen GOX IV, GOX IC
  • GAN IV, GAN IC internally compressed gaseous nitrogen
  • GAR IV, GAR IC internally compressed gaseous argon
  • the internal compression offers a number of technical advantages over an external compression of corresponding products, which is also possible in principle, and is explained in the specialist literature, for example from Häring (see above), Section 2.2.5.2, "Internal Compression".
  • EP 0 869 322 A1 discloses an air separation plant in which a single expansion turbine is used. In this a liquid stream is formed, which has a gas content of less than 5%. It is therefore a classic liquid turbine, as will be explained further below.
  • DE 32 16 502 A1 also discloses an air separation plant with a turbine, at the outlet of which there is essentially a liquid. A gas percentage should be a maximum of 10%. This turbine is one of several turbines. Another method in which a turbine is used, a small one at the outlet
  • the proportion of gas to be present is known from EP 3 312 533 A1. Further methods for air separation are disclosed in EP 1 189 003 A1 and EP 1 310 753 A1.
  • a turbine in which a two-phase mixture with a gas content of 10 to 50 mole percent, in particular 15 to 30 mole percent, is formed at the outlet is known from US Pat. No. 5,564,290 A.
  • the turbine has geometrical changes that allow a corresponding proportion of gas.
  • the turbine is one of several turbines and is to be fed with a fluid which is cooled to a temperature which is just below the liquefaction temperature when compressed to a subcritical pressure or just below the critical temperature when compressed to a supercritical pressure.
  • the object of the present invention is to improve the extraction of air products using air separation plants which are set up for internal compression and to make them simpler and less expensive.
  • a high-pressure air stream is expanded in an air separation plant. This stream is for vaporizing and warming up
  • the Joule-Thomson turbine thus takes on the role of an expansion valve, by means of which a so-called throttle flow into the conventional systems
  • a Claude turbine In the case of a double-column system, a Claude turbine is used to release compressed air that has cooled down from a higher pressure level to the pressure level of the high-pressure column and feed it into it.
  • cooled compressed air is expanded to the pressure level of the low pressure column and fed into it.
  • a Claude turbine is also referred to as a medium pressure turbine and a Lachmann turbine is also referred to as a low pressure turbine.
  • Claude and Lachmann turbines are supplied with compressed air at higher temperature levels than Joule-Thomson turbines, so that no (significant) liquefaction occurs during expansion.
  • the two turbines are also used in connection with air separation plants Called "gas turbines".
  • a Joule-Thomson turbine is used in conjunction with either a Claude turbine or a Lachmann turbine in air separation plants designed for internal compression. Even without a Joule-Thomson turbine, only a Claude or a Lachmann turbine can be used. In all cases, the use of appropriate turbines serves to compensate for
  • Liquids and gases can be rich or poor in one or more components in the language used here, "rich” for a content of at least 90%, 95%, 99%, 99.5%, 99.9% or 99.99 % and "poor” for a content of at most 10%, 5%, 1%, 0.1% or 0.01% on mole, weight or
  • Liquids and gases can be enriched or depleted in one or more components, these terms refer to a content in a starting liquid or gas from which the liquid or gas in question was obtained.
  • the Liquid or gas is "enriched” if it contains at least 1, 1, 1, 5, 2, 5, 10, 100 or 1,000 times, and “depleted "if this or this contains at most 0.9 times, 0.5 times, 0.1 times, 0.01 times or 0.001 times the content of a corresponding component, based on the starting liquid or gas. If, for example, “oxygen” or “nitrogen” is used here, this should also be understood to mean a liquid or a gas which is rich in oxygen or nitrogen, but does not necessarily have to consist exclusively of it.
  • Pressure levels and temperature levels can lie in disjoint areas or in areas that overlap one another.
  • pressure levels include, for example, unavoidable or expected pressure drops.
  • temperature levels The pressure levels given here in bar are absolute pressures.
  • Turbines contribute significantly to the construction costs of an air separation plant. Therefore, the number of turbines should be as low as possible from a manufacturing cost perspective. However, due to the energy savings that can be achieved, turbines reduce the operating costs of a corresponding system, so that there is a conflict of objectives. This is solved by the measures proposed according to the invention. By using the present invention, a reduction in the number of
  • the gas or steam content at the outlet of a Claude turbine or a Lachmann turbine is typically at least 90% (there is therefore a maximum of 10% liquid content).
  • Joule-Thomson turbines specifically designed as liquid turbines are typically operated without any gas or steam at the outlet, ie they are completely liquefied.
  • An essential aspect of the present invention is to use the Joule-Thomson turbine as the only turbine in a corresponding process, but to use it to expand into the two-phase area.
  • the present invention achieves the advantages already mentioned.
  • the present invention is particularly suitable for applications with a comparatively low cooling requirement, that is to say those processes in which comparatively small quantities of liquid products are provided and in which comparatively low internal compression pressures are present.
  • the present invention can be used in particular when forced rectification conditions are used, for example when comparatively large amounts of nitrogen-rich fluids are withdrawn from the high-pressure column.
  • blowing-in equivalent denotes the amount (in particular in mole fractions) of the air fed into the low-pressure column plus the nitrogen removed from the high-pressure column and exported from the air separation unit, in relation to the total, the
  • blowing-in equivalent is therefore defined as the amount of compressed air compressed and expanded by means of a blowing-in turbine into the low-pressure column of an air separation plant, plus the amount of nitrogen, possibly the high-pressure column
  • Air separation plant relaxed compressed air or the amount of nitrogen taken from the high pressure column and neither returned as a liquid return to the high pressure column itself nor given as a liquid return to the low pressure column can also be zero at a time.
  • the nitrogen withdrawn from the high pressure column can be pure or substantially pure nitrogen from the top of the high pressure column, but also a gas enriched with nitrogen or a corresponding one
  • Liquid that can be withdrawn from the high-pressure column from a region below the head with a lower nitrogen content Liquid that can be withdrawn from the high-pressure column from a region below the head with a lower nitrogen content.
  • a blowing-in turbine is used in a corresponding air separation plant and a quantity M1 of compressed air is expanded in this, a quantity M2 nitrogen is removed from the high-pressure column and removed as a liquid and / or gaseous nitrogen product from the air separation plant, i.e. not used as a return to the high and / or low pressure column, and a lot of M3 the compressed air
  • the present invention proposes a method of recovering an air product using an air separation plant with a rectification column system having a high pressure column operating at a first pressure level and a low pressure column operating at a second pressure level below the first pressure level.
  • the rectification column system can be designed in a basically known manner, in particular as a double column, or can comprise a corresponding double column.
  • the high and low pressure columns are connected via a main condenser, the top gas of the high pressure column is partially liquefied so that it can be returned to the high pressure column as a return line, and the bottom liquid of the low pressure column evaporates.
  • Main capacitor can be designed as an internal or external main capacitor.
  • Other configurations of the rectification column system are also possible in principle.
  • the rectification column system can be further
  • a first compressed air flow at a first pressure level and a second compressed air flow at a third pressure level which is above the first pressure level are provided and in each case at the first or third pressure level is subjected to cooling.
  • the usable pressure levels are explained in detail below.
  • the cooling can be particularly in one
  • Main heat exchanger of the air separation plant are carried out, from which the first and the second compressed air stream are supplied on the warm side and removed on the cold side.
  • the cooling takes place in particular at different temperature levels and in different passages of the main heat exchanger.
  • the first compressed air flow at the first pressure level can be subjected to cooling to a lower pressure level than the second compressed air flow at the third pressure level.
  • Compressed air streams are compressed in particular by means of a main air compressor on the one hand or by means of the main air compressor and a secondary compressor on the other hand, as also explained in detail below.
  • the first and the second compressed air stream consist of purified compressed air, which has been dried in a known manner and in particular has been freed from carbon dioxide and possibly other impurities.
  • the first compressed air stream is in the context of the present invention.
  • Rectification column system fed The feed is particularly in the high pressure column.
  • the second stream of compressed air is used using a
  • a material flow for example a compressed air flow
  • this material flow can also be subjected to part of these process steps as part of a material flow with a larger volume or volume flow.
  • the material flow mentioned in each case can be branched off at any point from the material flow with the larger volume or volume flow or at any point with a further material flow to the material flow with the larger volume or
  • Volume flow can be combined. It is also possible, for example, that a
  • Material flow with a larger volume or volume flow is first divided to form the material flow mentioned and the material flow mentioned is then combined again with other material flows to form a material flow with a larger volume or volume flow.
  • at least one more can Material flow together with the respective material flow are subjected to part of the specified process steps.
  • the first compressed air flow is fed into the rectification column system, which does not exclude that this first compressed air flow is initially part of a compressed air flow provided at the first pressure level with a larger volume or volume flow, of which the first compressed air flow before or after cooling is branched off.
  • the first compressed air flow is fed in particular into the high-pressure column, but this does not rule out that further compressed air at the first pressure level is also fed into the low-pressure column, even after a corresponding cooling.
  • the second stream of compressed air is blown onto the first using an expansion turbine
  • the pressure level is relaxed and fed into the rectification column system. This in turn does not preclude further compressed air from being treated in a similar manner and fed into the rectification column system.
  • part of the second compressed air flow can be generated by means of the expansion turbine and another part by means of a
  • Relaxation valve can be relaxed. This is intended to include the statement that the second compressed air stream is expanded "using" an expansion turbine, since this formulation does not indicate that the expansion is carried out using the expansion machine exclusively. In particular, however, the entire second compressed air stream is expanded to the first pressure level by means of an expansion turbine. However, this does not rule out that parts of it can then be further relaxed. In particular, the entire second compressed air stream can be fed into the rectification column system, in particular completely into the high-pressure column, but also partly into the high-pressure column and partly, after further relaxation, into the low-pressure column, previously also in particular in the high-pressure column Phase separation can take place and a liquid phase which forms in the process is immediate, ie especially in unchanged material composition as in the
  • High pressure column removed again, supercooled and can be relaxed in the low pressure column. This can already be the case in the prior art, as is the case is illustrated, for example, in FIG. 1, even if this is not explicitly shown in FIG. 1.
  • the expansion turbine which is used in the context of the present invention for expanding the second compressed air stream, can in particular be coupled or braked to a generator in order to be able to obtain electrical current in this way.
  • a generator in order to be able to obtain electrical current in this way.
  • the expansion turbine does not relax air to a pressure level below the first pressure level, the first
  • Pressure level could be passed.
  • the present invention is particularly suitable for use in processes by means of which internally compressed air products are provided.
  • the present invention therefore includes that a liquid stream from the rectification column system (the high-pressure column, the low-pressure column or a possibly existing crude or crude and pure argon column) is carried out, then increased in the liquid state by heating in the gaseous or
  • Air separation plant is diverted.
  • the liquid material flow can initially be part of a liquid material flow with a larger volume or volume flow, for example.
  • so-called internally compressed oxygen, internally compressed nitrogen or internally compressed argon can be provided in the context of the present invention.
  • a corresponding air separation plant can in particular also have units for known types of argon. Also a deployment of
  • a temperature level to which the second compressed air stream is fed to the expansion machine is at least 10 K, in particular at least 15 K or at least 20 K, below the critical level
  • the second compressed air stream is fed to the expansion machine at a supercritical pressure.
  • the two-phase mixture formed comprises a liquid phase and a gaseous phase. In principle, these phases can be separated from one another, for example after a settling in a separator. In the context of the present invention, the addressed
  • Expansion turbine which is otherwise basically comparable to a known so-called liquid turbine, as it can be used to expand a throttle current in a conventional system, so not completely
  • the expansion turbine which is used to expand the second compressed air flow or its portion, is the only expansion turbine that is used in a corresponding air separation plant.
  • the expansion turbine advantageously, in addition to the expansion turbine, in particular for
  • Expansion turbines are used which are operated in such a way that a pure gas phase or a two-phase mixture with a gas fraction of more than 80% is present at their outlet.
  • an air separation plant designed according to the invention can be constructed and operated particularly cost-effectively.
  • Total flow (which includes the gas portion and the liquid portion). A corresponding percentage is calculated, for example, from the quotient of gas flow and total flow (each in standard cubic meters per hour) multiplied by 100%.
  • Corresponding expansion turbine which relaxes in the two-phase region in the context of the present invention, requires a certain (extremely low) temperature at the turbine inlet. This can only be achieved by means of the Joule-Thomson effect during slow cooling of the system with reduced air flow and without the internal compression pumps being operated.
  • EP 0 869 322 A1 discloses an air separation plant in which a single expansion turbine is used. However, in this one
  • DE 32 16 502 A1 also discloses an air separation plant with a turbine, at the outlet of which there is essentially a liquid.
  • This turbine is also one of several turbines, so that there is no suggestion to make a change in the direction of the invention, in particular not to operate a single turbine as a Joule-Thomson turbine with an increased proportion of gas at the outlet.
  • a method or a corresponding system can be created within the scope of the present invention, which can manage with significantly lower investment costs and a comparable energy requirement. This is especially true when compared to a system with two turbines, namely a gas turbine (Claude or Lachmann turbine) in combination with a Joule-Thomson turbine that replaces the classic Joule-Thomson valve. Compared to a conventional configuration with only a gas turbine and a Joule-Thomson valve (i.e. without a Joule-Thomson turbine), there are even significant energy savings within the scope of the present invention.
  • a method according to a particularly preferred embodiment of the invention comprises either no liquid air products or liquid air products in an amount of not more than 1 mole percent, in particular not more than 0.5 mole percent, of that
  • Rectification column system total air supplied are discharged from the air separation plant. Such a comparatively low liquid production leads to the corresponding system having comparatively small amounts of cold is "withdrawn” by these air products and therefore the process or the system manages with relatively small amounts of additionally produced cold.
  • an “air product that is discharged from an air separation plant” is understood to mean a fluid that no longer participates in internal circuits, but rather leaves the plant completely.
  • Rectification column system total air supplied.
  • the present invention is particularly suitable for processes in which internally compressed air products are provided at comparatively moderate pressure levels.
  • a particularly advantageous embodiment of the present invention therefore includes that the air product described in the
  • Internal compression process is provided, is discharged from the air separation plant at a pressure level of not more than 50 bar, in particular not more than 40 or not more than 30 bar.
  • the present invention is used in particular in so-called main compressor / post-compressor processes, as have also been explained above.
  • the first compressed air stream is compressed to the first pressure level by means of a first compression device, or the air is provided at this first pressure level from the outside of the air separation system, for example by means of a so-called air rail at the installation site.
  • the second compressed air stream is first brought to the first pressure level by means of the first compression device or likewise provided externally at the first pressure level and then to the pressure device by means of a second compression device third pressure level further compressed.
  • Compression device if present, can, in the context of the present invention, in particular be separate compressors in the form of a
  • main air compressor and the post-compressor or the first compression device and the second compression device can also be integrated together in one machine.
  • a multi-stage compressor can be used within the scope of the present invention, from which the first compressed air flow at an intermediate pressure level and the second compressed air flow at an end pressure level can be taken. In this case it is the first
  • the compressor stages can in particular be driven in synchronism with speed or at different speeds using a common drive.
  • any combination of compression devices or compressors is possible within the scope of the present invention, by means of which a corresponding compression can be carried out.
  • a temperature level to which the second compressed air stream is cooled is in the context of the present invention at the outlet from the
  • the second compressed air stream is cooled to a temperature level below the condensing temperature at a corresponding pressure level or to a temperature level significantly below the critical temperature for supercritical pressures.
  • the first compressed air stream is particularly close to the liquefaction temperature of air on the first
  • Pressure level but cooled at a certain distance, for example from 0.5 to 10 K above this.
  • the second compressed air stream already experiences liquefaction or cooling due to its higher pressure.
  • the first compressed air flow at the first pressure level is cooled in particular more deeply than the second compressed air flow at the third pressure level.
  • the first pressure level is in particular 5 to 7 bar absolute pressure.
  • the second pressure level can be in particular 1.1 to 2 bar absolute pressure.
  • the third pressure level can be, for example, approximately 50 to 90 bar absolute pressure, in particular approximately 80 bar absolute pressure.
  • the third pressure level is therefore in particular at a clearly supercritical pressure of at least 10 bar above the critical pressure.
  • the first and second pressure levels are typical pressure levels as they exist in the high and low pressure columns of known double column systems of air separation plants; the third pressure level corresponds to a typically used post-compressor pressure in one
  • Forms expansion turbine which is used in the at least partial expansion of the second compressed air flow to the first pressure level, is partially or completely fed into the high-pressure column and a liquid fraction is separated therefrom in the high-pressure column, and that the liquid fraction is partly or completely passed through a supercooling counterflow the second
  • the second compressed air stream is expanded to the first pressure level partly using the expansion turbine and partly using an expansion valve.
  • Pressure levels in corresponding relaxation devices arranged in parallel can in particular also take place in different, variable proportions as required.
  • the first and the second compressed air stream are completely into the rectification column system
  • the first compressed air stream in the context of the present invention can comprise 60 to 80 mole percent and the second compressed air stream can comprise the rest of the total air fed into the rectification column system.
  • the present invention also extends to an air separation plant for obtaining an air product, comprising a rectification column system comprising a high pressure column configured to operate at a first pressure level and a low pressure column configured to operate at a second pressure level below the first pressure level is.
  • a rectification column system comprising a high pressure column configured to operate at a first pressure level and a low pressure column configured to operate at a second pressure level below the first pressure level is.
  • FIG. 1 shows an air separation plant according to an embodiment not in accordance with the invention in the form of a simplified process flow diagram.
  • FIG. 2 shows an air separation plant according to an embodiment of the invention in the form of a simplified process flow diagram.
  • liquid material flows are illustrated by means of filled (black) and gaseous material flows by means of unfilled (white) flow arrows.
  • FIG. 1 An air separation plant according to an embodiment not according to the invention is illustrated in FIG. 1 and designated 200 overall.
  • FIG. 1 An air separation plant according to an embodiment not according to the invention is illustrated in FIG. 1 and designated 200 overall.
  • Air separation plant 200 a compressed air flow a is provided and in two
  • Partial streams b and c divided.
  • partial flow b After dividing the partial flow b into partial flows d and e, these are fed to a main heat exchanger 3 of the air separation plant 200 on the warm side.
  • the partial flow d is taken from the main heat exchanger 3 at an intermediate temperature level, expanded in a expansion turbine 210, which can in particular be mechanically coupled to a generator or an oil brake, and into one
  • High pressure column and a main condenser 13 which connects the high pressure column 11 and low pressure column 12 in a heat-exchanging manner.
  • the expansion turbine 210 is therefore a typical Lachmann turbine, for which reference is made to the introductory explanations.
  • the partial stream e is led to the cold end through the main heat exchanger of the air separation plant 200 and then fed into a lower region of the high-pressure column 11.
  • the partial flow c is subjected to a post-compression in a post-compressor 4, which is followed by an after-cooler (not designated separately).
  • Sub-stream c is then divided into further sub-streams f and g, which are each fed to the main heat exchanger 3 on the warm side.
  • the partial flow f is led to the cold end through the main heat exchanger 3 and expanded by means of an expansion turbine 5 or an expansion valve 6.
  • the expansion turbine 5 is a so-called Joule-Thomson expansion turbine, for which reference is also made to the above explanations.
  • the partial flow g is the main heat exchanger 3 on one
  • the expansion turbine 220 is a classic Claude expansion turbine and is shown in the conventional one
  • Turbine outlet operated. After its expansion, the material flow g is combined with the material flow e in the expansion turbine 220 and fed into the lower region of the high-pressure column 11.
  • a material stream h is removed from the sump of the high-pressure column 11, passed through a supercooling countercurrent 8, and expanded into the low-pressure column 12.
  • Nitrogen-rich overhead gas in the form of a stream i is drawn off from the top of the high-pressure column 11, which is partly passed through the main condenser 11 in the form of a stream k and is at least partially liquefied in the process. Again a part of it is fed back in the form of a material flow I to the high pressure column 11, a further part is led in the form of a material flow m through the supercooling countercurrent 8 and fed in at the top of the low pressure column 12 as a return.
  • PAN pressurized nitrogen
  • Main heat exchanger 3 heated and thereby converted into the gaseous or supercritical state. In this way, one that is internally compressed here
  • Pressurized oxygen product (PGOX) can be provided.
  • a gaseous stream p is discharged from an intermediate region of the low-pressure column 12, through which
  • a liquid retention device in the head region of the low-pressure column 12 separates out nitrogen-rich liquid, which can be drawn off in the form of a material flow r and made available as a liquid nitrogen product (LIN).
  • a gaseous fluid drawn off from the top of the high-pressure column 12 can be conducted in the form of a material flow s through the supercooling countercurrent and through the main heat exchanger 3, heated, and provided as a low-pressure nitrogen product (LPGAN).
  • FIG. 2 An air separation plant according to an embodiment of the invention is schematically illustrated in FIG. 2 and designated 100 overall. Components already illustrated in FIG. 1 and present here for a comparable purpose are indicated in FIG. 2 with identical reference symbols and become the
  • ambient air (A) is also drawn in here by means of a main air compressor 1 via a filter 2 and compressed to a pressure level, which is referred to here as the “first” pressure level.
  • Preparation steps 20 which can include cooling and purification, the compressed compressed air, which is illustrated here in the form of a stream a as shown in FIG. 1, is divided into sub-streams b and c, the first sub-stream b being here as the "first" throughout Compressed air flow and the partial flow c
  • second compressed air flow are hereby referred to as "second" compressed air flow.
  • first compressed air stream b is passed through without further division into two partial streams
  • Compressed air flow c is from the warm end to the cold end through the
  • Main heat exchanger 3 out.
  • Compressed air stream c are thus cooled in the main heat exchanger 3 in separate passages, as explained above.
  • the first compressed air flow b is fed into the lower region of the high pressure column 11 of the rectification column system 10, the second compressed air flow c is generated using the expansion turbine 5 and the
  • Relief valve 6 to the first pressure level, but not to a lower pressure level than the first pressure level, relaxed.
  • the relaxed compressed air flow c here denoted by t, is fed here into the high-pressure column 11 as a two-phase mixture that forms at the outlet of the at least one expansion turbine 5.
  • a liquid fraction is separated therefrom in a suitable liquid retention device. This liquid fraction, here designated u, is at least partially withdrawn from the high pressure column 11 through which
  • the operation of the air separation plant 100 illustrated in FIG. 2 otherwise corresponds to the operation of the air separation plant 100 illustrated in FIG. 1. However, no further expansion turbines 210 and 220 are used, and expansion takes place in the expansion turbine 5 in such a way that a considerable proportion of gas is present at the outlet of the expansion turbine .
  • in particular low-oxygen nitrogen can be used on a
  • Pressure levels of 5 to 6 bar are subtracted in the form of stream i and partially made available as a product.
  • the pressure of the pump 9 of the material flow o is increased in particular to a pressure level of 20 to 40 bar.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

La présente invention concerne un procédé de production d'un produit formé à partir d'air au moyen d'une installation de séparation d'air (100) comportant un système de colonnes de rectification (10) qui comprend une colonne haute pression (11) fonctionnant à un premier niveau de pression, et une colonne basse pression (12) fonctionnant à un deuxième niveau de pression qui est inférieur au premier niveau de pression. Selon l'invention, un premier courant d'air comprimé est fourni à un premier niveau de pression et un second courant d'air comprimé est fourni à un troisième niveau de pression supérieur au premier niveau de pression, les courants d'air comprimé étant soumis à un refroidissement ; le premier courant d'air comprimé est injecté dans le système de colonnes de rectification (10) et le second courant d'air comprimé est injecté de manière détendue dans le système de colonnes de rectification (10) au premier niveau de pression, mais pas à un niveau de pression inférieur au premier niveau de pression, l'injection étant réalisée au moyen d'une turbine de détente (5) ; et un flux de matière liquide est extrait du système de colonnes de rectification (10) et est soumis à une augmentation de pression à l'état liquide, est transformé dans un état gazeux ou supercritique et est évacué de l'installation de séparation d'air (100) sous la forme de l'au moins un produit formé à partir d'air. L'invention est caractérisée en ce que le second courant d'air comprimé de la turbine de détente (5) utilisée lors de la détente du second courant d'air comprimé au premier niveau de pression est fourni à un niveau de température d'au moins 10 K en dessous de la température critique, en ce que ladite turbine de détente (5) est utilisée de sorte qu'un mélange biphasique se forme à la sortie de celle-ci, lequel présente, en sortie, une teneur en gaz comprise entre 5 et 25 % par rapport au mélange biphasique total, et en ce qu'aucune autre turbine de détente n'est utilisée dans le procédé aux fins de la détente d'air comprimé. L'invention porte également sur une installation de séparation d'air (100) correspondante.
PCT/EP2019/025280 2018-09-05 2019-08-21 Procédé de séparation cryogénique d'air et système de séparation d'air WO2020048634A1 (fr)

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EP18020430.7A EP3620739A1 (fr) 2018-09-05 2018-09-05 Procédé de décomposition à basse température de l'air et installation de décomposition de l'air

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3216502A1 (de) 1982-05-03 1983-11-03 Linde Ag, 6200 Wiesbaden Verfahren und vorrichtung zur gewinnung von gasfoermigem sauerstoff unter erhoehtem druck
US5564290A (en) 1995-09-29 1996-10-15 Praxair Technology, Inc. Cryogenic rectification system with dual phase turboexpansion
EP0833120A1 (fr) * 1996-09-25 1998-04-01 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé pour l'alimentation d'une unité consommatrice d'un gaz
EP0869322A1 (fr) 1997-04-03 1998-10-07 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé et installation de séparation d'air par distillation cryogénique
EP1189003A1 (fr) 2000-09-19 2002-03-20 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé et installation de séparation d'air par distillation cryogénique
EP1310753A1 (fr) 2001-11-10 2003-05-14 Messer AGS GmbH Procédé et dispositif pour la séparation cryogénique d'air
EP2963367A1 (fr) 2014-07-05 2016-01-06 Linde Aktiengesellschaft Procédé et dispositif cryogéniques de séparation d'air avec consommation d'énergie variable
EP2980514A1 (fr) 2014-07-31 2016-02-03 Linde Aktiengesellschaft Procédé de séparation cryogénique de l'air et installation de séparation d'air
EP3312533A1 (fr) 2016-10-18 2018-04-25 Linde Aktiengesellschaft Procédé de séparation de l'air et installation de séparation de l'air

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3216502A1 (de) 1982-05-03 1983-11-03 Linde Ag, 6200 Wiesbaden Verfahren und vorrichtung zur gewinnung von gasfoermigem sauerstoff unter erhoehtem druck
US5564290A (en) 1995-09-29 1996-10-15 Praxair Technology, Inc. Cryogenic rectification system with dual phase turboexpansion
EP0833120A1 (fr) * 1996-09-25 1998-04-01 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé pour l'alimentation d'une unité consommatrice d'un gaz
EP0869322A1 (fr) 1997-04-03 1998-10-07 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé et installation de séparation d'air par distillation cryogénique
EP1189003A1 (fr) 2000-09-19 2002-03-20 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé et installation de séparation d'air par distillation cryogénique
EP1310753A1 (fr) 2001-11-10 2003-05-14 Messer AGS GmbH Procédé et dispositif pour la séparation cryogénique d'air
EP2963367A1 (fr) 2014-07-05 2016-01-06 Linde Aktiengesellschaft Procédé et dispositif cryogéniques de séparation d'air avec consommation d'énergie variable
EP2980514A1 (fr) 2014-07-31 2016-02-03 Linde Aktiengesellschaft Procédé de séparation cryogénique de l'air et installation de séparation d'air
EP3312533A1 (fr) 2016-10-18 2018-04-25 Linde Aktiengesellschaft Procédé de séparation de l'air et installation de séparation de l'air

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* Cited by examiner, † Cited by third party
Title
F.G. KERRY: "Industrial Gas Handbook: Gas Separation and Purification", 2006, CRC PRESS

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